Yup. I've worked in the audio engineering industry for close to 25 years. During that time I've measured tons of loudspeaker speaker systems. Let me assure you, they are not "flat", not even the best of the best. If you want a flat response, you need to look at serious high end hifi gear...not something you'd play guitar through. The term flat response may be their way of saying "we aren't adding any extra EQ or DSP". It's certainly not a flat frequency response. No system is ever flat in a room and will change from room to room, even changing within the same room, depending on placement.
The other FR (full range) is also misleading. You don't really need a Full Range system for guitar. You need something that will operate from like 60Hz to like 12kHz. I think this is just to drive home the point that whatever comes out of the Helix is accurately reproduced by the loudspeaker.
All that said. There are tons of really good options. Just depends on what you want it to do.